Soldering for Engineers

Max Maxfield recently wrote "What? Electronics Engineers Who Cannot Solder?" Well Max, I too have a story about engineers and soldering. The following, which originally appeared in January 2013 on another UBM site (now offline), I reprint below. But, I'll go a step further and challenge Max to tell us if he has any scars from soldering, for I do. Read on.

I grew up around soldering irons and soldering guns, given my father's interest in CB and ham radio. I was soldering PL-259 connectors from about age 12 or so. At age 17, I acquired a scar on my left arm from a wave-solder machine while working in a printed-circuit board factory. I still have the scar.

Although I never had a formal course in soldering, I always considered it a required skill to become an electrical engineer. In college, a friend told me that at some companies, engineers weren't allowed to touch soldering irons. Union rules forced engineers to get a technician to solder even two wires together. I knew then that such companies were not for me.

This week, I learned that the Boston section of IEEE is offering a course in soldering. The course is given over two nights. Session 1 will cover things like types of soldering irons and choices of tip. The second session will give students a chance to solder components such as LEDs, transistors, and resistors.

The course description says that "Soldering is a must skill for all sorts of electrical and electronics work." That's certainly true, which is why I wonder if it needs to be offered at all. What am I missing here? Do today's engineers do all their work using software simulation and don’t build prototypes anymore? Well, I can understand if you’re designing ICs, for they're kind of hard to breadboard. That same holds true for, say, linecards where the signal bandwidths are too high for breadboards.

I find it almost incomprehensible that anyone working as an electrical engineer would feel a need to take this course. I can’t imagine life as an electrical engineer who doesn't know how to solder. Even after moving off the bench and into an applications engineering position, I always found a need to build a custom test cable or modify a board.

I've reached a point where it's hard to solder almost anything. I really need a lighted magnifier to solder. One time, I had to take off my glasses to see what I was doing. I could feel the heat from the iron on my face. That's a little too close.

Everyone complains about how hard it is to solder SMD, but I think that this has prevented a lot from trying. The truth is that it is really not all that hard. The reason I think that most fail at it is that they are trying to do it with a soldering iron. The first SMD device that I soldered was a 2mm x 2mm DFN8 part. I did it with solder past and a hot air rework station. I have yet to kill a part, and now and again, I need to retouch a single pin, but almost all the things that I have soldered in this fashion have functioned as expected right out of the box.

@Bert.... WE know that there is more to electronics than soldering itty-bitty thingies on boards. But the unwashed don't, and it';s still something that impresses them. So if it happens, quit while you're ahead. :-)

Your size for 0402 seemed pretty small....but it is right if you're using Metric sizes. 0402 imperial is actually 1 x 0.5 mm which is about the smallest thing I'd like to try soldering with my smallest 1mm tip.

Wikipedia has a nice table showing both sizes, if this does not come out here it'a at

SMT covers a pretty broad range of parts, some of which are more easily soldered or de-soldered with an iron, but others...not so much.

An 0402 chip resistor or chip cap is 0.4mm x 0.2mm -- roughly the size of each digit in the year on a U.S. dime. Sure, you can work with that if you have tweezers, a microscope and a fine tip on your iron. Temperature control & time is important too, since it's far too easy to lift the pads right off the PCB if you're not careful. But soldering these components is feasible -- techs do it all the time, so why not engineers?

On the other hand, try working with a high pin count BGA -- hundreds of solder bumps (balls), none of which is visible after soldering. There is a reason we have machines for that -- complete with optics & cameras for proper alignment to the PCB pads, a vacuum picker to handle the IC, and controlled, even heating to ensure all the hundreds of solder bumps melt at essentially the same time.

Yes, a soldering iron has its use for certain types of circuits -- mostly lower frequency stuff -- and certain types of components like passives, as well as ICs in soldering-friendly packages like through-hole, QFP, LCC and others where you actually have visibility and access to the pins that are to be soldered.

But is expert skill with a soldering iron a requirement for EEs working on hardware? Not always. It depends a great deal on the types of products you're working on.

First off, I can't imagine too many EEs who didn't start out, before college, being tinkerers of one sort or another. So I can't imagine too many that haven't mastered the basic skills in soldering. But it's a basic skill. Like tying your shoelaces, or I dunno, riding a bike. It's not something to dwell on.

As much as the average joe has no idea what engineers do to begin with, putting any emphasis on soldering is just, you know, embarassing. "Oh! That's what you do. You're the guys who solder those little thngies on little boards. Now I understand."

A lot of new graduates would argue soldering is not necessary because of SMT. "Who can really solder SMT?"

To me, soldering is a must have skill to all electrical/ electronics engineers, seriously, even software engineers in the embedded field. To my experience, there will always be a moment that you need to remove a componet to replace a component to test for example, the bootstrap configuration. At that moment, I would rather do it quick w/o waiting for any helps.

No doubt, soldering a SMT component isn't easy. Too much heat for too long might destroy the pad, too much solder will short the circuit. Not enough heat and time will keep the solder properly "glueing" the component to the pad. I encourage any new graduates who want to make a career in the field to take the course. It is fun to get your hand dirty and see the prototype board working.

> Do today's engineers do all their work using software simulation and don't build prototypes anymore?

Not always. Simulation can be very handy for flushing the bugs out of an idea, but once the simulation works it's time to heat up the soldering iron and breadboard it. Am in the simulation stage of a project right now, today will finish the schematic and order the components. Will be interesting to see how close the simulation correlates with the real thing.

There are certainly electrical engineering jobs for where soldring is required and won't help. For example, if you worlk on high-speed digital signals -- you know the 10Gbps kind and faster -- hand soldering on a board can have devastating effects on signal integrity. But even if that's your world, you should still know how to solder.